Unions have branded as unlawful proposals to allow non-governors to vote at school disciplinary committees dealing with child abuse allegations.
Both teachers' union the NASUWT Cymru and the National Association of Head Teachers' Cymru say legal challenges could follow if the proposal comes into force next February.
And Governors Wales, which represents the country's 26,000-plus school governors and supports the need for independent advisers, says it fears there are not enough people with sufficient expertise to help school governing bodies in dealing with allegations.
Speaking before Governors Wales's annual conference in Llandrindod Wells tomorrow, a spokesperson claimed non-governors' roles on disciplinary committees should be kept "strictly advisory".
Members of the body were part of a task force set up to find a consensus on how proposals in the far-reaching Clywch Report should be implemented.
In his report, children's commissioner Peter Clarke called for independent tribunals, chaired by lawyers, to investigate allegations of child abuse.
He believed it was the only way to help prevent "mistakes" made by key professionals following allegations of sex abuse against John Owen, a former drama teacher at Ysgol Gyfun Rhydfelen in Pontypridd.
However, the task force, made up of governors, unions and Welsh Assembly officials, rejected the recommendation. Instead, draft regulations proposing impartial outsiders with a legal background as a strong alternative have been put forward for consultation.
But Rex phillips, senior regional officer for the NASUWT Cymru, said:
"We're opposed to non-governors having voting rights because it gives that person employer rights they don't have."
A spokesperson from NAHT Cymru also said the proposal "flies in the face of employment rights given to properly-elected governors".
However, unions support the role of independent investigators.
Mr Phillips said: "We support an independent investigation service provided it's truly independent and seeks to prove all the facts."
The National Union of Teachers Cymru also insisted that outside expertise should be welcomed.
But Gethin Lewis, secretary, warned: "Many lay governors are busy people and haven't got the training or expertise needed to serve on a panel handling allegations of abuse.
"They will need to know the hurly burly of school life but also know about employment law and the principles of justice so everyone can feel they're having a fair hearing."
Peter Clarke, children's commissioner, said he was still convinced that his original proposals were the best option. However, he believed that a consensus among all interested parties on an alternative would lead to improvements."
At the Governors Wales conference tomorrow, keynote speaker Jane Davidson, education and lifelong learning minister, had been expected to endorse the organisation's code of conduct - a document which has been with the Assembly since February 2004.
But the official stamp of approval for the document, which outlines governors' roles and responsibilities, has been further postponed.
Anne Robertson, Governors' Wales development officer, said: "As far as we understand there's nothing major that they want to change, but it's irritating that it's not going to be endorsed as expected."